The etiology of prostate cancer is poorly understood, despite the fact that it is the second most common cancer among U.S. males. No clear patterns of causality have emerged from epidemiologic investigations of the conventional environmental factors, smoking diet, viruses and occupation. The importance of gonadal hormones on prostate growth regulation has suggested an obvious direction for inquiry; however, the nature of the association between gonadal hormones and prostate cancer risk has yet to be specified, as evidenced by conflicting findings reported in the literature. One reason is that most previous research has relied on measurements of serum hormone levels, without consideration of prostate tissue hormone receptor activity. It is proposed to develop a reliable autoradiographic assay for measuring levels of steroid hormone receptor content in normal, malignant and benign hyperplastic prostate tissue. The autoradiographic assay will be validated against existing biochemical techniques in animal and human tissue. The relative utilities of the autoradiographic and biochemical hormone receptor assays for epidemiologic research will be evaluated in a comparative pilot study on 20 patients with newly diagnosed prostatic adenocarcinoma and 20 patients with newly diagnosed benign prostatic hyperplasia. The two techniques will be compared with respect to reproducibility of results, ease of laboratory analysis, tissue requirements and cost. This pilot study will provide descriptive data on hormone receptor distributions, by age and race, among prostate cancer and benign prostatic hyperplasia patients. Additionally, serum levels of testosterone, progestagen and 17-beta-estradiol will be measured and correlated with autoradiographically and biochemically determined measurements of hormone receptor activity. The findings from this study will be used subsequently in the planning and conduct of multi-center case-control study of the associations between serum hormone levels, tissue receptor activity and risk for prostatic cancer in whites and blacks. Ultimately, study of receptor markers should enhance understanding of the etiology and pathogenesis of clinically apparent neoplastic disease arising from latent cancer, and provide a guide for therapy and prognosis.